Graph of the Day: Snout Position of the Gangotri Glacier, 1942-2008
A study of data from all available sources illustrates that the main trunk of the Gangotri glacier has been in a continuous state of recession during the past century. The length of the glacier has been computed for different years based on available data. The trend shows that the length of the glacier has reduced by almost 1.5 km in 67 years with an average retreat rate of 22.1 m/year. Consequently, there has been a gradual decline in the length of the glacier from 1942 to 2009. The glacier is not only receding in length but also in terms of glaciated area from all the sides. The possible reasons behind this retreat may be linked with two main factors: (a) reduction in snowfall and (b) an increase in the temperature of the region. With an average loss of 0.279 km2 per year, the glacier’s area has reduced by 17.84 km2, which comes to 25.33% of its area in 64 years since 1942 (see figure 3.3). It is evident that the reduction in the area was much slower between 1942 and 1976, with a loss of 3.19% in 35 years. However, the rate has increased subsequently and the glacier lost around 10.6% of its area in just 15 years (1976–1990). In the last two decades another 14.5% of the glacial area has been reduced. With a reduction in the area and length of the Gangotri glacier, there has been an obvious retreat in the snout position. Data collected from all the sources shows that this has been a continuous process; however, there have been fluctuations in the rate of retreat for different time intervals. The Gangotri glacier’s snout has retreated by about 1.5 km in the last 67 years (1942 to 2009) at an average rate of 22.21 m/yr. However, the actual retreat rates for different years vary considerably (see figure 3.4). During 1999-2006, the retreat rate came down to 5.6 m/yr, which may be due to an increase in snowfall during winters throughout this period as well as in earlier years because the glacier response time of Gangotri glacier is higher due to its larger size. …
